Adhesivity of bitumens for mineral aggregates



Patented July 19, 1949 ADHESIVITY OF BITUMENS FOR MINERAL AGGREGATES Felix C. Gzemski, Philadelphia, Pa., assignor to The Atlantic Refining Company, Philadelphia, Pa., a corporation of Pennsylvania No Drawing. Application November 7, 1944, Serial No. 562,407

6 Claims. (01. 106-273) This invention relates to a method of improving the adhesivity of bitumens to mineral aggregates, and relates more particularly to the preparation of improved road paving compositions.

The two methods generally used in the prep aration of bituminous pavements are, one in which a layer of bituminous cut-back or emulsion is spread on a road, a layer of mineral aggregate such as crushed stone, is spread upon it, and the mixture is compacted; and the other method is one in which mineral aggregate is first provided with a coating of bitumen by mixing the aggregate mechanically with a bitumen or bituminous cutback or emulsion until an adhesive coating of the bitumen is formed on each piece of the aggregate, the coated aggregate then being laid on the road and compacted. Where aggregate is used that has first been dried and hot bitumen or bituminous cutback applied to the aggregate, there is little difliculty experienced in securing a good bond between the bitumen and the aggregate, except with an acidic aggregate such as siliceous aggregates.

One of the objects of the present invention is to permit the coating of surfaces of damp or wet aggregates with a bituminous composition in such a manner that the coating obtained is satisfactory and produces a firmly bonded mass.

A further object of this invention is to prepare a paving mixture bonded with asphalt in which the asphalt coating, when applied to either dry or wet aggregate is not readily displaced or stripped when subjected to the action of water.

The present invention relates to a method of improving the adhesivity of bitumen to not only alkaline stones, such as limestone, slag, and dolomite, but also to acidic or siliceous type of mineral aggregates. Not only dry, but also wet aggregates may be successfully coated by the method of the present invention, and the pavings thereby prepared will not disintegrate under the action of water. It will be understood that the invention is especially advantageous in its application to the coating of wet mineral aggregates with bitumen, bituminous cutbacks, and bituminous emulsions.

Since adhesiveness is a consequence of wetting power, it is important that the wetting power of the bituminous binders toward the mineral aggregate be as high as possible. In the presonce of moisture or water, adhesiveness depends upon the respective wetting powers of water and the bituminous binder toward the mineral aggregate; if the wetting power of the water is higher than that of the binder, the former will displace the latter, and prevent the bituminous binder from adhering to the surface of the ag gregate. It is, therefore, an object of this invention to improve the adhesivity of the bituminous material as hereinafter described.

In accordance with the present invention, it has been found that the wetting power of bitumens to all types of mineral aggregates is markedly improved by incorporating in the bitumen a relatively small quantity of a cyclic nitrogen base sulfonate, and particularly a pyridinium or quinolinium salt of an oil-soluble hydrocarbon sulfonic acid. Pyridinium and quinolinium salts of oil soluble petroleum sulfonic acids, when added to bitumens in amounts of from 0.5% to 5.0% by weight, were found to be highly satisfactory in increasing the wetting power or adhesivity of the bitumens for aggregates. While larger quan= tities, for example, up to 10% of the salts may be used, the improvement in adhesivity is not increased proportionately, and it appears to be uneconomical in most cases to use more than about 5% by weight of the salts.

The salts or sulfonates employed in accordance with this invention are prepared by reacting oil-soluble sulfonic acids with a cyclic nitrogen base in an amount sufficient to at least partially neutralize the sulfonic'acids, and preferably to completely neutralize the acids. The oilsoluble sulfonic acids may be derived from petroleum oils, heavy coil tar distillates, fats, fatty oils, and the like by subjecting the raw mate- 7 rial to treatment with a sulfonating agent such as concentrated sulfuric acid, fuming sulfuric acid, chlorsulionic acid, or sulfur trioxide for a period of time sufficient to effect sulfonation, and

thereafter separating insoluble sludge from the oil containing the sulfonic acids. The oil solution of sulfonic acids is then neutralized with the cyclic nitrogen base to form a relatively insoluble cyclic nitrogen base sulfonate which may be separated from the oil and thereafter incorporated in the bitumen. The cyclic nitrogen bases which may be employed'include pyridine, the alkyl substituted pyridines such as the methyl and ethyl pyridines (lutidines), quincline, the alkyl substituted quinolines (quinaldines), isoquinoline, or mixtures of two or more thereof. In preparing the cyclic nitrogen base sulfonate, there is added to the oil containing the sulfonic acids an amount of nitrogen base calculated to give from 90% to 100% neutralization of the sulfonic acids, and the mixture is thoroughly agitated for a period of time sufficient to efiect neutralization. This operation may be carried out at ordinary temperature, but in order to render the separation of the nitrogen base sulfonate from the oil more rapid, the temperature of the mixture is preferably increased to 180 F.-220 F., a temperature of about 200 F. being quite satisfactory. The temperature is maintained within this range until the sulfonate begins to precipitate and settle, and the temperature is then reduced to 140 F.-160 F. and the oil is decanted from the sulfonate at this temperature. If desired, the sulfonate may be centrifugally separated from the oil, provided the temperature is maintained sufficiently high to prevent solidification of the sulfonate. At temperatures between 140 F. and 220 F. the sulfonate, which normally occludes some oil, is a viscous material which will flow at such temperatures, but at ordinary temperatures (70 F.) the sulfonate is solid. While it is preferred to effect separation of the sulfonate from the oil at elevated temperature, it is of course, possible to accomplish such result at ordinary temperatures, provided a sufficiently long settling period is employed. In the case of sulfonates prepared from relativel heavy oils or high boiling naphthenic oils, the precipitation of the sulfonates and the setting thereof from the oil may be facilitated by the addition of a small amount of water, for example, from 1% to 3% by volume of the oil.

For the purpose of the present invention, it is unnecessary to remove all of the oil from the sulfonate, since the presence of small quantities of entrained or occluded oil has little or no effect upon the properties of the bitumen to which the sulfonate is to be added. The sulfonate is relatively insoluble in oils which have been heavily acid treated, i. e., the oil after sulfonation for the production of the instant sulfonates, and is likewise relatively insoluble in paraifinic hy- .rocarbons or parafiinic oils, such as selective solvent treated lubricating oils or rafiinate fractions. However, the sulfonate is soluble in or at least compatible with bituminous materials such as petroleum asphalt or residuums, flux asphalts, coal tar pitches or residuums, cracking tars or residues, and aromatic or naphthenic hydrocarbons or oils such as benzene, toluene, and the higher homologues, as well as naphthenic extracts from the selective solvent treatment of lubricating oil stocks. In accordance with the present invention, the cyclic nitrogen base sulfonates may be incorporated in various bituminous materials such as asphalt, asphalt cutback, asphalt emulsions, etc., in order to increase the adhesivity of the bitumen for mineral aggregates.

The present invention may be further illustrated by the following examples,-which, however, are not to be construed as limiting the scope thereof.

1. A selective solvent extract fraction of a lubricating oil stock having a Sayboltv Universalviscosity of 524 seconds at 100 F. and an A. P. I. gravity of 17.3 was treated with 5 successive dumps of 5% by volume each of 98% concentration sulfuric acid, the acid sludge being settled and separated between each dump. To parts by weight of the sour oil containing about 12% of oil-soluble sulfonic acids was added 1 part by weight of quinoline, and the mixture was thoroughly agitated at about 80 F. until the neutralization reaction was completed. The mixture was then. settled and a dark colored precipitate of quinolinium sulfonate was separated I from the oil.

A road oil was made up comprising 34% of furnace oil (medium), 63% of penetration asphalt, and 3% of quinolinium sulfonate. Ten parts by weight of the road oil was mixed with 100' parts by weight of 20-60 mesh sand and 50 parts by weight of water, and despite the presence of the water, very good adhesion of the road oil to the sand was obtained. This asphalt coated aggregate, when placed in boiling water for one minute, did not strip, the asphalt remaining firmly bonded to the sand.

2. The procedure of Example 1 was repeated using a mixture of pyridines boiling from 284 F. to 392 F. in lieu of quinoline. It was found that of the pyridinium sulfonate incorporated in the road oil gave very good adhesion.

3. One hundred parts by weight of No. 3 mesh rock was thoroughly wetted with water, and a excess water was drained off. Five parts by wei ht of the road oil of Example 1 containing of pyridinium sulfonate in lieu of the quinclinimnsulfonate was added to the wet traprock and mixed at ordinary temperature until the road oil was distributed uniformly over the rock. The resulting aggregate was then mixed with an excess of water without causing the asphalt to strip from the rock.

According to the present invention, the bituminous material containing the cyclic nitrogen base sulfonate may be employed to treat a mineral aggregate so as to form only thin coatings on the aggregate so that it may be transported in aloose form to the point of use where further bituminous material is added and the mixture is applied in the usual road-building operations. The thin precoat overcomes the resistance to coating offered by some aggregates, and the pre coated aggregate is thus converted to an aggregate which is superior to those aggregates which are normally considered to be easily coated. However, the present invention is particularly adapted to the treatment of aggregates with road oils or cutbacks, such materials being used in the proportions ordinarily employed in the construction of pavedroads. and the like.

I claim:

1. A composition comprising a major proportion of bitumen and a minor proportion, suf-- ficient to increase the adhesivit of said bitumen for mineralaggregates, of a heterocyclic nitrogen base sa'lt of an oil-soluble sulfonic acid.

2. A composition comprising essentially bitumen and from 0.5% to 5.0% of a heterocyclic nitrogen base salt of an oil-soluble sulfonic acid.

3. A com-position comprising a major proportion of bitumen and a minor proportion, sufficientto increase the adhesivity of said bitumen for mineral aggregates, of a heterocyclic nitrogen-base salt of an-oil-soluble petroleum sulionic acid. w r

i ti.

FELIX C. GZEMSKI.

REFERENCES CITED The following referenlces are of record in the tile of this patent:

UNITED STATES PATENTS Number Name Date 2,130,668 Gunther Sept. .20, 1938 2,191,295 Dohse et a1. Feb. 20, 1940 2,314,111 Tucker Mar. 16, 1943 10 2,370,386 Anderson Feb. 27, 1945 2,375,055 Weetman May 1, 1945 FOREIGN PATENTS Number Country Date 543,625 Great Britain Mar. 5, 1942 847,829 France July 10, 1939 

